Asphalt Hot Box: How It Works + 7 Top Picks for 2026

Your crew loads two tons of mix at 7 a.m., hits three parking lots, and by the fourth stop what's left in the dump bed has set into a shovel-bending brick. 

An asphalt hot box solves that by holding the hot mix at working temperature for a full shift or longer, and a good one pays for itself in material savings within a season or two.

We pulled the current spec sheets, warranty terms, and published pricing from the major North American manufacturers, then compared the models on the four things crews shop for: mount style, capacity, heat source, and discharge.

Here's how these units work, what to check before you sign anything when your crew has outgrown a tarped truck bed, and the seven machines worth a spot on your shortlist this year.

The 7 Best Asphalt Hot Boxes: TL;DR

1. Falcon 4-Ton Hot Box Trailer: best all-around unit for crews patching every day
2. Spaulding 4-Ton Roadsaver: best for single-burner reclaiming with the oil-jacket option
3. KM International KM 4000T: best 2-ton starter trailer, with published lease figures
4. Stepp SPHD Dump Style: best for crews who'd rather dump than shovel
5. Falcon 6-Ton Hot Box Trailer: best for high-volume patching and wide utility cuts
6. Stepp SSPH Slip-In Hot Pack: best way to turn a truck you already own into a patcher
7. KM International KM 1000: best half-ton unit for cart paths, walkways, and tight access

What Is an Asphalt Hot Box?

An asphalt hot box is an insulated, heated hopper that holds hot mix asphalt at working temperature so a crew can patch all day off a single load. 

A diesel or propane burner feeds heat into a jacket or duct system around the hopper, insulation traps it, and a thermostat holds the material in the range where it still compacts.

You'll hear the same machine called a hot patcher, a premix heater, a pothole patcher, or a reclaimer, and like a lot of paving terminology, the name shifts by region.

Asphalt is only workable inside a narrow temperature window. 

Hot mix arrives on site somewhere around 275°F to 300°F, and your crew has to finish compaction before the mat drops below roughly 175°F. Past that point, the binder stiffens, the aggregate stops moving, and more rolling adds little density. A hot box gives you back the clock.

How an asphalt hot box holds temperature

Heat retention comes down to three things: the jacket, the insulation, and the controls. Many quality units run triple-wall construction with 2 to 3 inches of high-efficiency insulation, which is what KM International lists on the KM 4000T. Spaulding insulates every unit, doors included, with 1 inch of ceramic insulation instead. 

Falcon fires a Beckett burner into a one-piece ceramic combustion chamber and reports up to 48 hours of workable material along with 92% fuel efficiency on its trailer line.

Air-jacketed hoppers move hot air through ductwork and cost less. Oil-jacketed hoppers heat a fluid that wraps the hopper, so heat spreads evenly, and you avoid the hot spots that cook the oils out of your mix.

How a hot box differs from a reclaimer

A hot box holds material that arrived hot, and a reclaimer brings cold material back to working temperature. Plenty of machines do both, which is where the naming gets muddy on spec sheets.

Reclaiming works because stockpiled virgin mix still has its asphalt cement in it. Load the hopper, add a rejuvenator, run the burner low overnight, and you have workable material in the morning even with every plant in the county closed. 

Falcon's 3-ton and 4-ton trailers can be built with a second burner for recycling, and the 6-ton ships with two. Spaulding takes a different route on the 4-Ton Roadsaver: order the oil-jacketed hopper, and it reclaims with a single burner, which cuts fuel burn and leaves you one combustion chamber to service each year.

When Your Crew Needs an Asphalt Hot Box

Your crew needs an asphalt hot box when patch work stops being an afterthought and starts filling the calendar. The math turns in your favor fast once material waste and return trips to the plant become weekly line items.

The strongest use cases are the ones that stretch a single load across a full shift:

• Patching potholes and utility cuts across scattered commercial paving jobs
• Multi-stop punch-list days where each patch takes 20 minutes or so
• Shoulder-season and winter work when the nearest plant shuts down
• Small-quantity jobs where the plant minimum buries you in extra tonnage
• Reclaiming millings and leftover mix that used to go in the dumpster
• Warming cold patch so it's easier to work and compact

Falcon's 4-ton hot box page estimates that around 30% of hot mix cools in a dump truck before crews can use it. 

Treat that as a vendor figure, then run it against your own numbers. Two wasted tons a week comes to 8 or 9 tons a month, which at current mix prices covers KM's $239 monthly lease figure on its own.

A hot box changes your dispatch more than your paving. The unit has to get loaded, assigned, and towed to the right stop in the right order, and one blown sequence strands a hot load at the wrong address. 

Six or eight patch stops a day is the point where whiteboards and group texts quit working, and where automating the coordination side starts to pay. The box makes money on the days your crew hits every stop, and it loses money on the days it sits in the yard loaded.

The office side adds up too: rebuilt schedules, re-keyed invoices, and property managers calling to ask which lot your crew patches Tuesday. A client portal cuts those calls by letting managers check status, approve changes, and see invoices online. If that's your office, a OneCrew demo shows how scheduling, billing, and the customer portal run in one platform.

Signs you've outgrown a tarped truck bed

• You're throwing away material most weeks
• Your crew makes two or more plant runs a day
• Cold patch callbacks keep landing on your desk
• Winter work goes to competitors because you can't get hot mix
• Shoveling out of a raised dump bed is wearing your people down

When to skip it: you may not need one yet if you run a paver crew on full lots and only patch a few times a season. If the plant also sits 10 minutes away and stays open most of the year, a tarped bed, tight scheduling, and the right truck count from our asphalt trucking calculator can carry you another season. 

Buy the box once the waste and the windshield time add up to more than the machine costs. It's the same test you'd run on tools built for contractors: weigh the fix against the workaround you've been living with.

Types of Asphalt Hot Boxes

Hot boxes come in three mounting styles: trailer, truck-mounted, and skid or stationary.

Trailer-mounted hot boxes

Trailer units run from 1 to 6 tons. Smaller sizes hook to a pickup, while Falcon's biggest trailer, the 6-ton, is rated to 20,000 pounds GVWR and needs a heavy-duty tow vehicle. The advantage is separation: drop the trailer at the job and keep your truck free for material runs and dump work. 

Spaulding builds 2-, 3-, 4-, and 6-ton trailers, and Falcon runs the same four sizes with a waist-high unloading height, so your crew isn't reaching up into a raised bed all day.

Truck-mounted and slip-in units

Truck-mounted hot boxes turn a chassis you already own into a patch truck. Falcon offers slip-in, hook-lift, and chassis-mounted configurations up to 10-ton capacity on its truck-mount line, and Stepp builds oil-jacketed slip-ins sized for the small trucks already in your fleet. 

One truck, one operator, no trailer to back into a tight lot. The trade-off is dedication: a permanent mount claims that truck most of the season, while a slip-in can come off between patch jobs.

Skid-mounted and stationary units

Skid units drop into a pickup bed or a UTV and handle the work bigger machines can't reach, like cart paths, sidewalks, and interior walkways. 

Stationary boxes live at the yard and hold bulk material at temperature between jobs. Neither replaces a trailer for parking lot work.

How We Picked These Asphalt Hot Boxes

Everything below comes from current manufacturer spec sheets, warranty terms, options lists, and published pricing. Nobody handed us a unit for a week on a patch crew, so get a dealer demo and put hands on the machine before you sign anything.

What moved a unit onto the list:

• Published specs a buyer can check, including capacity, weights, GVWR, and BTU ratings
• Real heat retention claims backed by insulation and combustion details
• Discharge options that fit crew size, from gravity shovel doors to hydraulic dump
• Ergonomics, because shovel height drives fatigue and comp claims
• Warranty and parts support through a dealer network you can reach
• Fit for commercial paving contractors, from parking lots to municipal and utility bids

Asphalt Hot Box Comparison

The 7 Best Asphalt Hot Boxes and Hot Box Trailers in 2026

1. Falcon 4-ton asphalt hot box trailer

The Falcon 4-Ton Hot Box Trailer hits the sweet spot for commercial paving contractors who run patch work as a real service line, week after week. Four tons covers a 12-foot by 13-foot repair at 4 inches deep, or about 160 one-foot-square potholes, which is a full day of patching for most crews.

Falcon fits a 33-inch full-width material door and a heated shoveling apron at waist height, so several people can work the hopper at once. 

Key specs:

• 4-ton capacity on a 16-foot standard frame, with 14-, 18-, and 20-foot options
• Single diesel or vapor-draw propane burner, with an optional dual-burner recycling package
• One-piece ceramic combustion chamber (on the diesel model) and automatic temperature control
• Optional dump box, hydraulic doors, 30-gallon tack tank, and compactor basket

Pros

• Heat holds up to 48 hours, so overnight loads stay workable
• Waist-high, full-width unloading is easier on backs over a long shift
• Heated apron gives shovel access for quick fixes, with no dump required

Cons

• Recycling costs extra as a dual-burner package
• Pricing is quote-only, through Falcon or a local dealer

2. Spaulding 4-ton Roadsaver hot box trailer

The oil-jacketed Spaulding 4-Ton Roadsaver reclaims asphalt on a single burner. 

Spaulding points out that air-jacketed hoppers need two burners for the same job, which means more fuel and a second combustion chamber on the annual service list.

Spaulding builds the hopper heavy: a quarter-inch steel floor, 10-gauge inner panels, and 12-gauge outer walls, with a sloped design that feeds material toward the rear door so your crew does less shoveling. 

Automatic temperature control comes standard; the diesel burner (propane is the alternative) is rated at 105,000 BTU, and the dumping hopper option adds two hydraulic cylinders when shoveling gets old.

Key specs:

• 4-ton hopper in air-jacketed or oil-jacketed configurations
• Diesel or propane, with 105,000 BTU on the diesel burner
• Quarter-inch hopper floor, 10-gauge inner panels, 12-gauge outer walls
• Tandem axles, electric brakes, and a 12-position adjustable hitch

Pros

• Burns less fuel on overnight reclaiming runs
• Oil jacket heats evenly and protects the binder in your mix
• Heavy steel build holds up under daily loading

Cons

• The oil jacket isn't standard, so spec it when you order
• No published pricing, so you request a quote from Spaulding or a dealer

3. KM International KM 4000T

For a first proper asphalt hot box trailer, the KM 4000T is the easiest entry point, and KM is one of the few manufacturers that publishes what financing looks like. 

The company lists monthly payments from $239 on 60-month lease terms through third-party lenders, which gives you a number to run against your material waste before you ever call a rep.

Two tons suits a two- or three-person crew working a patch route. Triple-wall construction with 2 to 3 inches of insulation holds temperature up to 48 hours, and the unit reclaims bulk-stored mix overnight. 

KM mounts the burner and key components above the frame inside a steel enclosure; KM credits the same layout on its 4-ton 8000T with preventing road-debris damage and premature burner failure.

Key specs:

• 4,000-lb capacity, 2,180 lbs empty, 7,000-lb GVWR single axle
• Propane at 58,000 BTU or diesel at 105,000 BTU
• Triple-wall construction with 2 to 3 inches of insulation
• 2-year parts and workmanship warranty, 5-year trailer frame warranty

Pros

• The only pick on this list with a published monthly payment
• Tows behind a properly rated pickup
• Protected burner placement cuts service headaches

Cons

• Two tons runs short for full-day, multi-crew patching
• The 52-degree dump is an extra-cost option

4. Stepp SPHD dump-style premix heater

Crews tired of shovel lines should look at the Stepp SPHD. 

A truck-style scissor hoist dumps the hopper at a 50-degree angle, and Stepp balances the trailer so the 12,000-pound electric-over-hydraulic hoist needs no outriggers, which saves setup time on every stop.

The oil-jacketed hopper and diesel burner give you even heat, and when you dump straight onto the road, the shoveling platform folds up out of the way. 

Stepp offers it in 2.0 cubic yard (3-ton) and 3.0 cubic yard (4-ton) sizes, and the low-profile hopper keeps the center of gravity where you want it on a tandem-axle trailer.

Key specs:

• 3-ton or 4-ton capacity, in 2.0 and 3.0 cubic yard hoppers
• Diesel burner with automatic temperature controls
• Oil-jacketed heating system and recirculating internal exhaust
• Hydraulic dump standard, plus optional hydraulic top and discharge doors

Pros

• Hydraulic dump moves material fast on larger patches
• Optional 220V electric heat keeps mix warm overnight
• Handles small potholes or large utility cuts from one unit

Cons

• Diesel burner only, so propane crews look elsewhere
• Hydraulics add components to service

5. Falcon 6-ton asphalt hot box trailer

Falcon's biggest trailer, the 6-Ton, earns its keep on wide utility cuts and municipal contracts where a crew burns through material by noon. Six tons covers roughly a 15-foot by 16-foot repair at 4 inches, or about 240 small potholes per load.

Every 6-ton unit ships with a two-burner system, so recycling millings and chunks comes standard with no upgrade to add. 

Hydraulic dump is standard too, which you'll want at this size, and triple-wall construction with the one-piece combustion chamber keeps heat even across a hopper that big.

Key specs:

• 6-ton capacity, the largest in Falcon's trailer line
• Two diesel burners standard for recycling and even heat
• Hydraulic dump function standard
• Automatic temperature control and heated shoveling platform

Pros

• Rated at 92% efficiency, so more of each gallon goes into heating the mix
• One load covers a full day of heavy patching
• Same waist-high shoveling design as the smaller Falcons

Cons

• Needs a serious tow vehicle and a rated hitch
• Overkill for crews patching a few times a month

6. Stepp SSPH slip-in hot pack

The Stepp SSPH Slip-In Hot Pack turns a truck you already own into a patcher, which appeals to anyone who has run out of yard space for trailers. 

Stepp sizes it at 1 cubic yard (1.35 ton), 2 cubic yards (3 tons), and 3 cubic yards (4 tons), with slip-in, hook-mount, and truck-mount configurations.

It shares the SPHD's oil-jacketed hopper, diesel burner, and folding shoveling platform. 

Stepp builds it for low manpower needs, so you don't have to keep a big crew standing by. In slip-in form, it needs no special truck setup or dedication, so the truck isn't locked into patching all season.

Key specs:

• 1.35-ton, 3-ton, and 4-ton hopper sizes
• Diesel burner with automatic temperature controls
• Oil-jacketed heating system for even heat
• Slip-in, hook-mounted, or truck-mounted, with hoist options

Pros

• No trailer to tow, back up, or store
• The 1-yard size is built for the one-ton tilt beds many crews already run
• Small crews can run it, which keeps labor costs down

Cons

• The 1-yard unit needs a forklift or overhead lift to get onto the truck
• Mounting and hoist options complicate the quote

7. KM International KM 1000

The KM 1000 goes where nothing else fits. At 59 by 34 by 34 inches and 375 pounds empty, it drops into a pickup bed or a utility vehicle and holds 1,000 pounds of material, which makes it the pick for golf cart paths, park trails, and smaller walkways.

A 60,000 BTU propane burner heats it, triple-wall construction holds temperature, and it reclaims material like its bigger siblings. Half a ton disappears quickly on parking lot work, so treat this as a second unit for the jobs your trailer can't reach.

Key specs:

• 1,000-lb capacity, 375 lbs empty
• 59 by 34 by 34 inches
• 60,000 BTU propane burner
• Triple-wall construction with 2 to 3 inches of fiberglass insulation

Pros

• Fits sites where a towed unit can't turn around
• Tapered inside walls feed mix straight to the shovel port
• Thermostatic control holds temperature without anyone watching the burner

Cons

• Half-ton capacity limits it to small repairs
• Propane only, so diesel fleets add a second fuel to manage

What to Look for Before You Buy an Asphalt Hot Box

Capacity you'll use every day

Size the box for the day you run most often, then rent or sub out the outliers. Pull last season's patch tickets and look at average tonnage per day, along with how often you sent someone back to the plant. 

That number picks your capacity faster than any brochure will. If you don't have tickets to pull, our asphalt tonnage calculator turns a repair's length, width, and depth into tons. Oversized boxes cost you twice: once at purchase, then every day in fuel to heat a hopper you never fill.

Diesel or propane burners

Diesel burners push more heat. KM rates its trailer burners at 105,000 BTU against 58,000 to 60,000 BTU on propane, and diesel pulls from a tank your fleet already fills. 

Propane wins on simplicity, and for plenty of crews, a bottle swap beats waiting on a fuel-system service call. Ask your dealer which burner their techs see fewer problems with in your climate, then believe the answer.

How the material comes out

Discharge method decides how your crew spends the day. Gravity discharge through a sloped hopper and shovel door costs less and gives you fewer parts to break. 

Hydraulic dump empties a hopper in seconds and suits larger patches. Auger discharge meters material out under power, which municipal crews favor on long runs of utility cuts.

Insulation and steel that survive a season

Read the numbers on the spec sheet and ignore the brochure adjectives. Triple-wall construction with a stated insulation type and thickness is what to look for, and hopper steel matters as much: a quarter-inch floor with 10- or 12-gauge walls takes daily loading without warping. 

Ask where the burner sits, too. A burner mounted above the frame inside an enclosure stays out of the dirt, debris, and salt that wear down one hanging underneath.

Tow ratings and payload math

Do this math before you fall in love with a model. KM's 2-ton 4000T weighs 2,180 pounds empty, so 4,000 pounds of mix puts it at about 6,200 pounds loaded on a trailer rated for 7,000 pounds. Part of that load rides on the hitch as tongue weight, which counts against the truck's payload along with the crew and their tools, and that rules out some half-ton pickups. 

Skid and slip-in units need payload capacity in the truck itself. Get the loaded weight in writing from the dealer and compare it against your door-jamb sticker.

What an Asphalt Hot Box Costs

Most hot box manufacturers price by quote, through the factory or a dealer, and published sticker prices stay rare because options move the number so much. 

KM International gives you the clearest published starting point: monthly lease payments from $239 on the 2-ton KM 4000T and from $529 on the 4-ton KM 8000T, both based on 60-month terms through third-party lenders.

Canadian crews should also look at Novilco, which custom-builds trailer and slip-in units and services them through a Canadian distribution network.

New or used: how to decide

Buy new if the box will run a daily patch program and you want full warranty coverage and the options you specify, and plan for a build queue if the model you want isn't in stock. Buy used if you need a unit next week at a lower price and can live with an unknown service history. 

Manufacturers list their own trade-ins, and Falcon, KM, and Spaulding all keep used inventory pages, which beats a marketplace listing with three blurry photos.

What to inspect on a used hot box

1. Burner system: watch it fire, check the flame pattern, and confirm the safety shutoff works
2. Insulation: look for wet, compressed, or missing insulation, since heat loss shows up in your fuel bill
3. Hopper steel: hunt for warping, burn-through, and weld repairs on the floor and lower walls
4. Doors and seals: cycle the loading and shovel doors, and replace tired seals before the first cold snap
5. Frame, axles, and brakes: check for cracks at the tongue, brake function, and tire dates
6. Controls: verify the thermostat reads accurately against an infrared gun
7. Fuel system: inspect the tank, lines, and fittings for weeping and corrosion

Bring a technician who knows burners. An inspection that catches a cracked combustion chamber is the cheapest money you'll spend on the machine.

Asphalt Hot Box Tips for Loading, Maintenance, and Patch Pricing

Treat the hot box like a profit center, starting with how you load and heat it.

Load it full and keep it hot, because partial loads cool faster and cost nearly as much to heat. If your unit has an overnight timer, use it so material comes up to temperature before the crew clocks in, which turns a slow morning into a productive one.

Track tonnage, burner hours, and crew hours against each patch so the next round of bids runs on real numbers. Price that work on margin: to clear a 20% margin on $1,000 in job cost, the bill has to be $1,250. Adding 20% on top of cost only gets you to $1,200, a 16.7% margin, and patch work has too little room for that gap.

Ten minutes with a scraper and some release agent at the end of the shift saves an hour of chiseling out a cold shovel door next week. Same story with the burner: service the combustion chamber and flues on the manufacturer's schedule, since a fouled chamber burns more fuel and heats unevenly.

Know the limits of the machine, too: a hot box can't bring back mix that was scorched by overheating, and it can't make a cold patch product behave like properly compacted hot mix. 

The repair still depends on prep: clean out the hole, square the edges where it makes sense, tack, fill, and compact in lifts. Once the patch cures, a quality sealcoat protects the surface from UV and oxidation, and our sealcoating equipment guide covers the gear to apply it.

Price, Schedule, and Bill Hot Box Patch Work With OneCrew

OneCrew is a platform built specifically for project-based commercial asphalt and concrete paving contractors, including crews that also run crackfilling, striping, and snow work. It ties your patch work operation together from lead to invoice, so the estimator, the yard, and the office all work from the same job. 

Trusted by top contractors across North America, OneCrew has helped propose more than $8B in projects and cut estimating time by 75%. 

Here's what it covers:

• Price every patch job accurately before the hot box ever leaves the yard: OneCrew's estimating tools cover site and/or plan mapping and measurement, then build bids with calculators that work out tonnage, materials, and trucks.
• Schedule your crew and hot box across the day's jobs without double-booking anyone: OneCrew's scheduling feature assigns specific crew members and equipment to each job and flags conflicts before you save.
• Get work orders and site details to the crew before they load out: The job site management tools push mobile work orders, GPS directions, and job specs to crew phones and pull time, photos, and production data back to the office as each job closes.
• Know your real margin on every patch: OneCrew's job costing compares your estimate against what your foreman submitted from the field, covering labor, materials, and trucking.
• Send proposals property managers can approve before a competitor follows up: OneCrew's proposals feature generates professional, branded proposals directly from your estimate.
• Track every repeat account so no maintenance cycle slips through the cracks: OneCrew's CRM keeps every lead, follow-up, and customer relationship in one place.
• Invoice the same day the patch closes and sync to QuickBooks without double entry: OneCrew's invoicing tools generate invoices from the line items already in the platform.

Book a demo to see how commercial paving contractors run estimating, scheduling, job costing, and invoicing for patch work in one platform.

FAQs

What is an asphalt hot box?

An asphalt hot box is an insulated, heated hopper that holds hot mix asphalt at working temperature during transport and storage. A diesel or propane burner and a thermostat keep material workable so crews can patch potholes and utility cuts all day from one load.

How long does an asphalt hot box keep asphalt hot?

An asphalt hot box keeps asphalt hot for up to 48 hours on Falcon and KM International trailers, and Spaulding claims up to 72 hours in a fully oil-jacketed box. Insulation thickness, jacket type, and outside temperature all affect real-world retention, so treat those figures as best cases.

What size asphalt hot box do I need?

Most commercial paving contractors need a 2- to 4-ton asphalt hot box. A 2-ton unit suits a small crew on a patch route, 3- and 4-ton trailers cover typical commercial work, and 6-ton units fit crews running heavy municipal or utility contracts.

Is an asphalt hot box trailer better than a slip-in unit?

An asphalt hot box trailer works better when you want to drop the unit at a job and free up your truck, and a slip-in works better when yard space is tight or you'd rather run one vehicle. The trailers on this list top out at 6 tons, while Falcon's slip-ins run all the way up to 10 tons.

Can you tow an asphalt hot box trailer with a pickup?

You can tow a 2-ton asphalt hot box trailer with a properly rated pickup, since a loaded KM 4000T weighs roughly 6,200 pounds against its 7,000-pound GVWR. Check your truck's tow rating, hitch class, and tongue weight limit first, and plan on a heavier truck for 4-ton units like the KM 8000T, which carries a 14,000-pound GVWR.

Can you rent an asphalt hot box?

Yes, you can rent an asphalt hot box from paving equipment dealers and rental yards. Crafco Supply Centers rent hot box asphalt patchers, and regional dealers like The McLean Company rent units such as the Falcon 4-ton trailer. Renting for a few weeks is a low-cost way to test whether your patch volume justifies buying.